/Engine/Source/Runtime/Engine/Public/Rendering/SkeletalMeshLODModel.h
It also use a private mutex to make sure it's thread safe to copy the same source multiple time in multiple thread.
static void CopyStructure ( [FSkeletalMeshLODModel](API\Runtime\Engine\Rendering\FSkeletalMeshLODModel) * Destination, const [FSkeletalMeshLODModel](API\Runtime\Engine\Rendering\FSkeletalMeshLODModel) * Source )